Conventionally, branch tee fittings for piping have typically been fabricated by bulge forming using lead. However, the branch tee fittings thus fabricated bring high fabrication costs and other problems.
To solve such problems, a branch tee fitting is proposed which can be fabricated by subjecting a plate such as a copper plate to press forming (see, for example, Patent Document 1: Japanese Patent No. 2660427). This branch tee fitting is shown in FIGS. 8(A) to 8(C). FIGS. 8(A) and 8(B) are front and side views of a branch tee fitting (100), respectively, and FIG. 8(C) is a vertical mid-sectional view of the fitting shown in FIG. 8(A).
The branch tee fitting (100) includes: a tubular body portion (101) having a pair of openings at both ends; and a tubular branch portion (102) perpendicular to the tubular body portion (101). The tubular body portion (101) and the tubular branch portion (102) are formed in such a manner that one plate is bent, and along a plane inclusive of the center line of the tubular body portion (101) and the center line of the tubular branch portion (102), facing edges of the bent plate are joined in superposed relation.
In the branch tee fitting (100), the tubular body portion (101) has a substantially U-shaped cross section passing through the center of the tubular branch portion (102) (the middle position of the tubular body portion (101)), and has a substantially C-shaped cross section at both end locations thereof. In angles between the tubular body portion (101) and the tubular branch portion (102), flat portions (103) are provided, respectively, in which corners of the plate are superposed to each other. The branch tee fitting (100) is joined to pipes (P) in such a manner that with the pipes (P) inserted into the tubular body portion (101) and the tubular branch portion (102), respective joint faces of the fitting and the pipes, including the matching faces of the flat portions (103), are brazed at one time.